Gun mount with foldable firing control frame



IJan. y4, 1949. J, H, KOCHEVAR v 2,457,824 l GUN MOUNT WITH-FOL-DABLE FIRING CONTROL FRAME Filed May 4, 1945 I 3 SheetS-Sheet vl Jan. 4, 1949.

Fiied May 4, 1945 3 Sheets-Sheet 2 vnf/149% an. 4, l949. vL H, KOCHEVAR 2,457,824

GUN MOUNT WITH FOLDABLE FIRING CONTROL FRAME Filed May 4. 1945 3 SheetsSheet 3- INVENTOR. T .JOLLN LL. KOCLLLVAQ 1:1 T Tom/ERS.

Patented Jan. 4, 1949 UNITED STATES PATENT f OFFICE GUN MOUNT WITH FOLDABLE FIRING CONTROL FRAME amended Aprill 30, 1928;v 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the paymentI to me of any royalty thereon. I l

This invention relates to a gun mount. More particularly it relates to a portable mount intended to be emplaced by being simply set upon a at ground surface for carrying a light caliber antiaircraft gun for free tracking of targets. As a brief designation of such a mount, it may be termed a ground set mount.

In order that a light caliber gun, such as a cal. .50 machine gun, may be as effective as possible against a variety of targets, and particularly against aircraft, it is desirable that it be mounted in such a manner that it will have free swinging in traverse and elevation or depression through maximum ranges. Likewise, the gun must be characterized by means providing for the control and ring thereof in any of its innitepositions, A

requisite consideration being given to the safety and comfort of the gunner. In addition, consideration has been here given to other struc,- tural details of the weapon with the object of making it easily transportable, of lightweightconstruction, readily emplaced and stable while fir-- lng.

It is accordingly an object of the present in vention to provide a gun mount on whichsa gun may be mounted for free swinging in azimuth and in elevation or depression, particularly in elevation, and in which means are provided for facilitating the ring of the gun at exceedingly low command height regardless of its position on the mount.

It is an important object of the invention to provide a gun mount having an elevator or pedestal in which the mount for the gun is laterally offset from the pivotal mount' of the elevator on the base so that the breech of the gun may be swung as closely as possible to the elevator or pedestal to permit the achievement of maximum elevation. y

Among other objects, advantages and features of invention, held in View are the following: p

a. To effect a mount construction whereby the gun may be trunnioned with a low center of gravity so as to reduce material andrweight of pedestal and secure great stability in proportion to material required, and to reduce the required radius of a polypod mount.

b. Adaptation of the gun to be elevated close to the zenith and traversed through 3,60 degrees in azimuth by a standing or squatting soldier, notwithstanding that the gun .trunnions are much 2 below waist-level, and that a simplesingle `member pedestal is employed. f n

c. To construct an exceedingly light weight mount which will -alord a gun support of adequate rigidity for safe and stable pointing ofthe gun during rapid fire. l f f d. To embody a mount withthe foregoing qualities which is specially adaptedto be -made readily and quickly into a small package readily portable as a unit and which may safely be dropped by parachute from an airplane, aswell as rapidly assembled. v l

e. To enable operation of the gun alternatively at will by a foldable extension grip and trigger or conventionally -by grip and trigger immediately at the back plate or butt of the gun receiver.r

f. To attain special fitness in an antiaircraft gun and mount for use by airborne troops.

g. To eliminate interferen-ce of mount legs with movements of a gunner in traversing the gun.

The invention has for another important object the provislonfof firing control mechanism including a ring control'frame foldable withrespect to the gun and mount during transport and for certain types of firing, and extensible to facilitate ring of the weapon at maximum elevation; in this respect, the invention hasy for another object means for releasably retaining or locking the ring control mechanism in either position.

Other objects of the invention are to provide a mount of lightweight and `sturdy construction; to provide a mount that may be easily disassembled for transport and quickly assembled or set up for firing;v and to provide operating mechanism including a plurality of firing grips by which the weapon may be fired from more than one point on the ring control'means. f 'a The foregoing and other objects will become apparent from the following detailed description of a preferred embodiment'of the invention; and modifications thereof, as illustrated in the accompanying sheets of vdrawings in which:

Fig. 1 is a side elevation ofthe mountwith a gun positioned thereon and further with the gun shown in its position of maximum elevation as indicated in broken lines; the ligure also shows in broken lines the folded position of the firing control means;

Fig. 2 is a plan View of the mount shown in Figure 1, the gun having been omitted from the.

gure; v Fig. 3 is a longitudinal sectional view on an enlarged scale taken on the line'3-3 of Fig. 2 and showing the details of construction ofthe firing lcontrol mechanism and operating means therefor;

Fig. 4 is a fragmentary perspective view showing the foldability and extensibility of the frame structure comprising the ring control means;

Fig. 5 is a view similar to that shownin Fig. 3 but illustrating a modified form of operating mechanism for the ring control means;

Fig. 6 is a fragmentary view of the structure shown in Fig. 5 on the line 6-6 of Figure 5, looking in the direction of the arrow;l

Fig. '1 is a fragmentary perspective view of the rear end portion of the gun illustrating generallyl the actuating member operable by the firing control means on the mount.

'Ihe particular embodiment of the invention chosen for the purposes of the present description comprises a base Il preferably formed as a cast#- ing and having a plurality of horizontally 'dis posed sockets II. are four sockets which serve to receive `respectively the inner ends of four supporting legs I2. Each socket II is provided with quickly releasable and attachable clamping means I3 by which the legs are readily and quickly attached to or detached from the base II). Each leg is provided at its outer end with a spade I4 which is adapted to engage the ground in the usualmanner to stabilize the base I0. That is to say, the spades may be :pressed into ordinary earth by the gunners foot, and the legs I2 will then rest upon the ground directly. The spades prevent sliding of the mount or rotation thereof. The legs maybe pressed down also, so that the bed plate forming the bottom of the base I may be adjusted onthe ground surface, sustaining a substantial load and affording amore stable support. Similarly when the gun is set on an earth pier with a surrounding annular trench of the same radius as the spades, the legs-by reason of their approximately horizontal positions and the function of the bottom of the base IO--may be adjusted so as to come to rest firmly on the top of thepiery whereas with inclined leg construction, they crumble off the edges of the pier and cause upset of the gun, or delay and impair its emplacement accommodation. Usually such mounts involve such command height that if the span of the foot 4portions is reduced to avoid interference with the gunner, the gun will be too unstable for` use. A wide radius of legs precludes the practicable use of a gun for antiaircraft ilre in a protective annular trench of the kind indicated, as well as impairing its use on ordinary elds, by interfering with movements of the gunner in tracking.`

The gun mount furtherincludes a generally upright elevator or pedestal I having a lower mounting portion I6 angled with'respect to the vertical and mounted rotatably on the base by means of a bearing indicated' generally at I1. The intermediate portion of the elevator I5' comprises a vertical column I8 formed with a vertical bore (not shown) withinwhichis received the vertical shank (not shoWn)'-of amounting yoke I9. The upper end of the column'IU is formed as a flange 2D having a transverse recess 2I into which the lower portion 2| of the yoke I9 ts. This construction mounts the yoke I9 von the ele# Vator I5 for rotation as a unit about the vertical pivot I1 between the elevator I5 and the base I0. A securing clamp 22 is threaded into the side of the column I1 and engages the shank of the yoke I 9 for removably and rigidly securing the `yoke and elevator together.

The yoke I9 is curved upwardly and inthe d- In the present instance there .a pair of longitudinally spaced transverse bottom or web portions 25 (Fig. 2), at opposite sides of each of which is an upstanding wall portion 26 extending longitudinally or normal to the axis of the trunnions 23. The rear end of the cradle 24 is provided with means, such as a pair of oppositely disposed bolts 21 passed respectively through the side walls 26, by which the cradle 211 carries a rearward extension 28. For the purposes of the present disclosure, the cradle 24 and extension 28 will be considered as part of the same unit, the importan-c-e of the connection be may be removed for disassembly of the cradle components. The cradle extension 28 includes a pair of opposite rearwardly diverging frame portions 29 having parallel rear ends, provided with downwardly extended parallel parts 29 rigidly cross connected by a transverse frame portion 3U. The right-hand frame member 29 (as viewed from behind the gun) includes a laterally extending manipulating or gun-pointing grip 3 I. The lefthand frame member 29 is provided with a combined manipulating and operating grip 32 (Fig. 2) for operating the firing mechanism of the gun as Well as aiding in gun pointing. The grip 32 is rockably mounted on the 1eft-hand frame portion 29 by means of a shaft or bolt 33, the inner end of which has keyed thereto, or otherwise secured thereto for rocking therewith, a lever arm 34 (Fig. 3). This arm 34 is pivotaily connected by an adjustable link35 to a bell crank 36, carried on a pivot 31 on a vertical extension support 38,'at the left side of the cradle ex tension 28. The extension support 3B carries thereon an actuator indicated generally at.39. This actuator may be of any conventional construction and includes a longitudinally reciprocable, spring-pressed plunger 40, the outer end of which is pivotally connected by a short link 4I to the bell crank 36. Rocking of the bell crank 36 von its pivot 31 is imparted by the link 4I to the plunger 40, which in turn effects longitudinal reciprocation of an actuator plate 42 provided with an actuating lug 43. As will b-e hereinafter brought out in detail, the actuator 39 is operatively associated with the ring mechanism of a gun mounted on the cradle.

Each of the frame portions 29 of the cradle extension 28 is directed upwardly at its rearward en'd to provide a vertical frame member or supn port stud `44 (Fig. 4). The supports 44 serve to carry thereon a firing and gun pointing frame extension indicated generally at 45 (Fig. 3) This extension may be termed a gun operating frame, and comprises a pair of transversely spaced tubular members 45, each of which is provided at one end with a longitudinal slit 41. As best shown in Figs. 1 and 4, the members 46 are respectively mounted on the supports 44 of the fran-1e portions 29 by means of pivot pins 48, the lower portions or corners of the supports 44 respectively fitting into the slit portions of the members 46 so that the' extension frame 45 may be swung from a position folded beneath the cradle 24 (broken lines in Fig. l) to the upright orgun operating position shown in Figs. l and 3, for example. The upper end of the extension frame 45 is provided with a transverse member 49 rigidly cross connecting the members 46. The upper right-hand side of the extension frame 45 is provided with a manipulating or gun pointing grip 50, which may be similar to the lower manipulating grip 3l. The upper transverse member 45 of the extension frame 45 is provided with a transverse bracket 5|, which has formed integrally therewith a pair of transversely spaced upstanding ears 52, in which is carried a transverse rod 53. One end of the rod projects at the right side of the extension frame 45 and serves as means by which the manipulating grip 56 is secured to the extension frame. The other end of the rod 53 projects at the left side of the extension frame 45 and carries rockably thereon a combined manipulating or gun pointing and operating or gun firing grip 54, similar to the operating or gun ring grip 32 previously referred to. The manipulating grips are rigid members by which swinging of the gun in tracking is eiected, and the other two, while aiding in the swinging of the gun, in addition serve as triggers or gun actuators, firing the gun. The rod 53 carries thereon, intermediate the grip 54 and proximate ear 52 of the bracket 5|, a sleeve 55 formed with a depending lever arm 56. An operating rod or link 51 is provided at its upper end with a clevis through which a bolt or pin 58 is passed to connect the rod or link 51 pivotally to the arm 56 on the sleeve 55. The inner end of the manipulating and operating grip 54 is keyed or otherwise secured to the sleeve 55 so that the rocking of the grip 54 effects rocking of the sleeve 55 and arm 56. The operating link 5l extends downwardly and is curved inwardly and then again downwardly so that it lies within the extension frame 45, and is provided at its lower end with a clevis 59 and pin 66 for pivotal connection to a lever arm 62 carried loosely on the pin or bolt 33 previously described as carrying the manipulating grip 32 and lever arm 34. The lever arm 34 carries rigidly th-ereon a projecting stud or pin 63 engageable by the underside of a hooked nose portion 64 thereover formed on the forward end of the lever arm 62.

From the description thus far, it will be seen that rocking of either of the grips 52 or 54 will effect vactuation of the link 35, bell crank 36 and actuating plate 42. Rocking of either of the grips 32 or 54 to reciprocate the actuating plate 42 is in a clockwise direction, as viewed from the right side of the mount. Because of the lost motion connection 63-64 between the lever arm 34 and the lever arm 62, the actuator plate 42 may be reciprocated by the lower manipulating grip 32 independently of movement of the upper grip 54.

It was previously stated that it was an important object of the invention to provide ring control means mounted for movement from a folded position beneath the cradle to an upright positionV of pins 48 is coincident with the axis of pin 66.1

Because of the slots 4l in the members 46, the extension frame has free movement with respect to the cradle extension 2 8. The internal diameter- 6 of the tubular members 46 is'equal to the width of the supports 44. This arrangement provides for the construction yand use of a simple means for releasably securing the extension frame 45' in its upright position asl illustrated in Figs. 1 and 3. This `securing means includes a pair of sleeves 65, one being'slidably carried on one tubular member 46, and-the other being similarly carried on the other tubular member46. As illustrated in Figs. 1, 3 and 4,'the`sleeves 65 are adapted to embrace the lower portions of the members 46 and the respective extension'supports 44,"so that, whenthe extensionframe 45 is in 'its upright position, the extension supports will be confined within the slots 41 of the member 46, and within the downwardly positioned sleeves 65". Re-A lease of the frame extension 45 for swinging movement downwardly is effected by upward' positioning of the sleeves 65 so that the extension supports 44 may be freed from their locked positions with respect to the members 46. As shown in brok-en lines, the frame extension 45 may be folded (Fig. l)k beneath the cradle 24 and cradle extension 28. The right-hand frame member29, of the cradle'extension 23, is provided with releasable securing means in the form of av spring clip 66 engageable with the right-hand tubular member 46 when the frame extension45 is-movedr to the lower position indicated. f

As shown in Fig. l, the cradle 24 is provided with a pair of longitudinally spaced transversely extending removable ymounting pins 61 and 66 which pass through openings inthe opposite side members 26 of the cradle 24 and into mounting openings in the receiver 9 of the gun lcarried by th-e mount. Themou'nting of the gun `on the cradle, as just described, is` of a well known type and need not be set forth in greater detail. The gun 8 illustrated is shown generally in the patent to Browning, No. 1,628,226, and is the only Inachine gun of .50 caliber used in all branches of the Army, and Air Forces of the United Statesvin the present war. Various adaptations to special, uses were made in which the proportions ofthe receiver and gun mechanism remained the same in all cases. The form illustrated has a lquick dismountable barrel 8, the fastenings of which comprise no novel part of .the present invention, and therefore are not illustrated although useful for compactness when the gun is` shipped inV knocked down form, especiallywhen it is to bel dropped from airplanes. IIn vthe 4latter use it is usually accompanied by airborne troops (onei ofthe important, uses made of this gun and mount). Fig. 'l illustrates in perspective kthe rear and left side of the receiver 9 of av conventional. type machine gun. There is illustrated in thm figure means, other than the usualtrigger, for actuation of the firing mechanism of the gun. This actuating means may assume vany desired forni.- v -That herein illustrated is but one ofk many conventional types and is therefore not shown in connection with the interior mechanism of the gun.

In brief, the adapter vmeans of the type hereinj shown is connected to the-firing mechanism in-f. side the receiver of the gun and includes la reciprocable lug 69 at the exterior left side of the receiver. When the gun is mounted on the cradle 24, the lug 69 is aligned with and behindtheacsingle actuating trigger, usually provided on thev gun, had been utilized.

In the modified form of ring control mechanism shown in Figs. and 6, the essential dilerences over the construction shown in Figs.

1, 2 and 3 are in the manipulating grips and the actuating linkage. In the modified form the extension frame 45 is provided at its right side with the upper manipulating grip 50 and the cradle extension 28 is provided at its right side with the manipulating grip 3 The cradle extension 28 is provided at its left side with a rigidly mounted manipulating grip which is substituted for the rockable combined operating and manipulating grip 32. The grip 10 Yhas Ypivotally mountedY thereon a depressible lever 1| which is provided at its inner end with a downwardly and inwardly curving actuatingy member 12 engageable with a rlip 13 preferably formed integrally with a longitudinally extending lever 14. This lever isrockably mounted on the left-hand frame member 29 by means of a pin or bolt and takes the place of the lever arms 34 and 62 of the construction shown inFig. 3. The lever 14 is connected at its forward end to a link 16 which is in turn connected to the bell crank 36. The rear end of the link 14 is pivotally connected by means of a clevis 11 and pin 18 to a vertically extending operating rod 19, the upper end of which is pivotally connected to the inner end of a depressible handle or lever 80, pivotally carriedon an upper manipulating grip 8| on the extension frame 45. The grip 8| is rigidly carried by the left-hand tubular member 46 of the frame and takes the place of the rockable grip 54, previously described in connection with the construction shown in Fig. 3. It will be noted that either of the levers or handles 1| or 8D may be pressed to effect actuation of the linkage comprising the rod 19, lever arm 14, link 16 and actuator mechanism 36--43. In other words, each grip 10 or 8| and respective lever 1| or 80, provides a grip that may be squeezed by the operator for ring the gun.

The use and operation of the weapon is substantially th-e same Whether the extension frame 45 be equipped with either the rockable manipulating grips 54 and 32 or with the squeezable grips 1li- 1| and Bil-8|. When th-e Weapon is emplaced for general ring in which the field of lire is mainly horizontal, the extension frame 45 may be folded to the position shown in broken lines in Fig. 1, in which position it will be retained by the releasable securing means comprising the securing clip 66. 'Ihls would be the practice in case the gunner is seated or prone on the ground on which the mount is set, and also in case the mount is set on the pier formed by an annular trench in which the gunner may stand just beyond the ends of the legs. It may be seen that the legs have a radius which closely approximates that of the extremity of the cradle extension with respect to the axis of traverse of the gun. In use on a trench pier as mentioned, if there is liability of straling by enemy airplanes, the gunner may keep the extension frame erected and locked, so that he may change from use of the lower grips 3|-32, to use of the grips 50-54 at will for overhead targets, without interruption of tracking. Even though the extension frame 45 is in this position, there will be no interference with the functioning of the firing control mechanism as operated by the lower left-hand grip 32 (1U-1| The arrangement of the opposed grips 3| and 32 (1U-1|) is such that the operator may the linkage.

track the weapon by grasping one grip with each hand and may aim the Weapon or continue tracking with his right hand on the right-hand grip 3| while rocking the left hand grip 32 (squeezing the grip 'FU-1 l) with his left hand. It will be noted from an examination of Fig. 1 that even with the extension frame 45 folded beneath the cradle 24. the gun will still have a relatively large range in elevation. The offset relationship between the upper and lower mounting portions of the elevator I5 with respect to the intermediate portion thereof provides for this maximum elevation and at the same time there is no interference whatsoever with the ability of the weapon to track in azimuth.

vIt will be noted that the arrangement between the firing control linkage and the pivotal mounting of the extension frame 45 is such that the extension frame may be swung from one of its positions to the other without any interference with This result follows from the coincidence of the extension frame mounting pivot #i8 and the pivot Gil between the vertical rod 51 and the lever arm 62 (Fig. 3). The same relationship between pivots occurs in the construction shown in Fig. 5, wherein the pivotal mounting 48 of the frame extension 45 is coincident with the pivot 18 forming the connection between the vertical arm 19 and the rockable lever arm 14.

When the gun is used as an antiaircraft weapon, it will be found desirable to extend the frame 45`to its upright position. As previously stated, it may be locked in this position by the securing sleeves 65. Since the firing of the weapon in defense against aircraft will necessarily involve firing at or near maximum elevation of the gun, tracking and iiringfof the gun will be accomplished through use of the upper grips 50 and 54 (B0-8|). This position of the extension frame 45, as extended, will enable the operator to track the weapon with considerable ease and even at maximum elevation of the weapon he will be required to assume, at most, the relatively comfortable squatting posiion. In such position his feet will be free of the legs |2 on the base l0 so that he can move freely about the mount'without tripping over the legs of the mount.

In case the gun is mounted in a revetment or analogous trench form, the folded arrangement of the extension frame may be used while the gun is set on an earth pier. For airborne attack operations, however, such emplacements are usually impossible and the extension frame, coordinated with the low mount has been found of marked value.

In the training 0f such weapons, on moving targets, heretofore, correction for proper lead has customarily been derived principally from observation of tracer paths, and this practice can be readily carried out with my improvement. The initial lay of the gun may be estimated from the same factors heretofore governing antiaircraft fire with open sight guns, and carried out as in operating firearms from the hip. In squatting, as may happen in case of extreme elevation of the weapon, the gunner remains on his feet and ready to rise if necessary. He may step laterally While in this squat position to accommodate azimuthal changes of angular position of the target.

The invention has been used with .50 caliber machine guns of a form previously standard, which is illustrated in Figure 1.

From the proportions of the gun used on this mount it will be seen that the height of the trunnions (which are nearly even with the bore axis) above the ground is approximately 27 inches, whereas, with a single grip set gun, in which the grips are immediately at the rear of the receiver it has heretofore been thought necessary to have the trunnions at a height of 60 inches for'antiaircraft fire. While it has heretofore been found practicable to adapt a lower mount to antiaircraft fire, the best required an elaborate system of trigger framing and four sets of triggers and grips, while the present device has eliminated much of the bulk, weight, and grip devices heretofore used on those mounts. The prior lowest portable antiaircraft tripod mount adapted for the particular gun illustrated had a trunnion height of 36 inches. Said mount weighed 313 lbs.; the instant mount weighs 125 lbs.

Improvements looking to the simplification and reduction of weight of an antiaircraft machine gun mount for use `by airborne troops have lately been attempted, owing to the need for rapidly bringing such weapons into action by newly landed airborne troops in the open while exposed to enemy fire. The best prior development submitted proposed a sixty inch trunnion height, weighed 165 lbs. and required at least fifteen seconds longer to set up for action. It was found too unstable for adoption. These attainments together and separately are factors of high importance each and all marking valuable advances.

An important advantage derived from the lowering of trunnion height in such a gun is, that it has been possible to shorten the radius of the legs and spades (as in Figures 1 and 2) so that the gunner, in operating the gun, may move in a circular path beyond the spades, and so will not trip or stumble over the legs of spades, which has been a serious difculty with the prior developments of portable antiaircraft tripod mounts for such a weapon as here shown.

Although I have shown and described a preferred embodiment of my invention, with one modication thereof, it will be apparent that other modifications and alterations may be made in these preferred forms of the invention without departing from the spirit and scope thereof as defined in the appended claims.

I claim:

1. A gun mount for machine guns and the like, comprising a gun cradle having right and left rearwardly diverging frame portions terminating rearwardly of a gun mounted in said cradle, a generally rectangular extension frame comprisinge parallel side members and a transverse member rigidly connecting said side members adjacent one of their ends, each said side member being pivoted at its other end, on a common first axis, upon the rear end of a respective frame portion, whereby said extension frame may be pivoted from a first upright position at the rear of and extending above said gun, to a second position beneath and closely adjacent said cradle, a lower grip carried by one said frame portion, a first lever pivoted on said one frame portion on a second axis, means responsive to pivotal movement of said first lever in one direction only to re a gun carried by said cradle, an operating connection between said lower grip and first lever, a

second lever pivoted on said second axis, a lost motion connection between said levers whereby motion of said second lever in said one direction only correspondingly pivots said first lever, an upper grip on said extension frame having a part pivoted on a third axis, and a link connected to said part at one end and pivoted at its `other end to said second lever on an axis normally coincident with said first axis, whereby either grip may be used to lire said gun.

2. A gun mount for machine guns and the like, comprising a gun cradle having right and left rearwardly diverging frame portions terminating just rearwardly of a gun mounted in said cradle, a generally rectangular extension frame comprising parallel side members and a transverse mem- :ber rigidly connecting said side members at one of their ends, each said side member being pivoted at its other end on a common first axis, upon the rear end of a respective frame portion, said first axis being transverse of a gun mounted in said cradle, whereby said extension frame may be pivoted from a first substantially vertical position with said transverse member above the level of a gun in said cradle, to a second position wherein said frame is underneath and closely adjacent said cradle, right and left lower grips on said frame portions forwardly of said first axis, one said lower grip being pivoted on a second axis parallel with said first axis, a lever connected with said one lower grip, means responsive to pivoting `of said lever in one direction to fire a gun mounted in said cradle, a second lever pivoted on said second axis and adjacent said rst lever, a lost motion connection between said levers whereby pivoting of said second lever in said one direction only also pivots said first lever, right and left upper grips on said frame above said transverse member, one said upper grip being pivoted on a third axis, and a link connection between said pivoted upper grip and said second lever, said link connection being pivoted to said second lever on an axis normally coincident with said first axis whereby said extension frame may be pivoted to said second position without affecting said levers.

JOHN H. KOCHEVAR.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 394,190 Koerner Dec. 11, 1888 628,840 Normand July 11, 1899 1,436,536 Russell et al Nov. 21, 1922 1,558,566 Rockwell Oct. 27, 1925 1,701,153 Green Feb. 5, 1929 1,740,907 Schuler et al Dec. 24, 1929 2,030,389 Negrotto Feb. 18, 1936 2,175,931 Trim-bach Oct. 10, 1939 2,370,835 Bell et al Mar. 6, 1945 FOREIGN PATENTS Number Country Date 369,212 Italy March 15, 1939 

